login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A262519 Odd bisection of A155043. 7
1, 2, 3, 4, 3, 4, 5, 5, 6, 7, 7, 8, 6, 9, 10, 11, 11, 12, 13, 13, 14, 15, 14, 15, 10, 16, 17, 17, 18, 19, 20, 19, 21, 22, 22, 23, 24, 23, 25, 26, 15, 16, 16, 17, 18, 18, 19, 19, 20, 20, 21, 22, 21, 22, 23, 23, 24, 24, 24, 25, 21, 26, 22, 23, 23, 24, 24, 24, 25, 26, 26, 27, 27, 27, 28, 29, 28, 30, 31, 31, 32, 33, 32, 33, 28, 33, 34, 29, 35, 36, 37, 37 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Number of steps needed to reach zero when starting from k = 2*n + 1 and repeatedly applying the map that replaces k by k - d(k), where d(k) is the number of divisors of k (A000005).

LINKS

Antti Karttunen, Table of n, a(n) for n = 0..10000

A. Karttunen, Ratio a(n)/A262518(n) drawn with the help of OEIS Plot2-script

FORMULA

a(n) = A155043(2*n + 1).

MATHEMATICA

Table[Length[NestWhileList[#-DivisorSigma[0, #]&, n, #!=0&]]-1, {n, 1, 200, 2}] (* Harvey P. Dale, Aug 31 2017 *)

PROG

(Scheme) (define (A262519 n) (A155043 (+ n n 1)))

CROSSREFS

Cf. A000005, A049820, A155043, A262518, A262520, A262521, A262681.

Sequence in context: A216197 A307531 A125619 * A225320 A308937 A123066

Adjacent sequences:  A262516 A262517 A262518 * A262520 A262521 A262522

KEYWORD

nonn

AUTHOR

Antti Karttunen, Oct 02 2015

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 16 18:03 EDT 2019. Contains 328102 sequences. (Running on oeis4.)